How to Begin Implement Stateless Routing in NS3

To implement the Stateless Routing in networking suggest to the routing approach in which no state information for instance routing tables or path histories is handled at nodes for routing decisions. Typically, stateless routing protocols depend on basic devices such as geographic routing or source routing, in which all necessary routing data has involved the packet itself.

Here’s how you can begin implementing a Stateless Routing Protocol in NS-3:

Steps to Begin Implement Stateless Routing in NS3

Step 1: Understand Stateless Routing

1. Key Characteristics:
   • State manages at intermediate nodes or no routing tables.
   • Routing decisions are based on only data carried in the packet.
   • General approaches include:
     • Geographic Routing: Depend on the geographic coordinates to sending the packets.
     • Source Routing: The source node has contains the complete path in the packet header.
2. Advantages:
   • Low memory consumption in the nodes.
   • Scalability for dynamic networks.
3. Challenges:
   • Packet overheads are high in all routing information must be embedded in the packet.
   • It needs the further devices for failover and managing the dynamic network topology.

Step 2: Set Up NS-3

1. Install NS-3:

git clone https://gitlab.com/nsnam/ns-3-dev.git

cd ns-3-dev

./ns3 configure –enable-examples –enable-tests

./ns3 build

1. Verify Installation: Run a sample script:

./ns3 run examples/tutorial/first

Step 3: Plan Stateless Routing Protocol Design

1. Core Components:
   • Packet Header: Embed routing information for instance path or destination coordinates in the packet.
   • Forwarding Logic: Use the packet data for chooses the next hop.
   • Failure Handling: Stop the packets or retry by different paths for sending fails.
2. Implementation Workflow:
   • Express the custom packet header has contained the routing information.
   • Apply the sending a function for establish the next hop according to the packet header.
   • Encompass the NS-3’s Ipv4RoutingProtocol class for manage the routing decisions.

Step 4: Implement Stateless Routing

Step 4.1: Define the Custom Packet Header

Build a custom header to transmit the routing information:

#include “ns3/header.h”

#include “ns3/ipv4-address.h”

#include <vector>

using namespace ns3;

class StatelessRoutingHeader : public Header {

public:

static TypeId GetTypeId(void);

virtual TypeId GetInstanceTypeId(void) const override;

virtual void Serialize(Buffer::Iterator start) const override;

virtual uint32_t Deserialize(Buffer::Iterator start) override;

virtual uint32_t GetSerializedSize(void) const override;

virtual void Print(std::ostream &os) const override;

void SetPath(const std::vector<Ipv4Address> &path);

const std::vector<Ipv4Address> &GetPath() const;

private:

std::vector<Ipv4Address> m_path; // Full path or other routing information

};

Step 4.2: Implement the Stateless Routing Protocol

Spread the Ipv4RoutingProtocol class:

#include “ns3/ipv4-routing-protocol.h”

#include “ns3/stateless-routing-header.h”

#include <map>

using namespace ns3;

class StatelessRouting : public Ipv4RoutingProtocol {

public:

static TypeId GetTypeId(void);

StatelessRouting();

virtual ~StatelessRouting();

virtual Ptr<Ipv4Route> RouteOutput(Ptr<Packet> packet, const Ipv4Header &header,

Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) override;

virtual bool RouteInput(Ptr<const Packet> packet, const Ipv4Header &header,

Ptr<const NetDevice> idev, UnicastForwardCallback ucb,

MulticastForwardCallback mcb, LocalDeliverCallback lcb,

ErrorCallback ecb) override;

private:

void ForwardPacket(Ptr<Packet> packet, const StatelessRoutingHeader &header);

};

Step 4.3: Implement Core Functions

• RouteOutput: Assign the routing information for packets in the source node.

Ptr<Ipv4Route> StatelessRouting::RouteOutput(Ptr<Packet> packet, const Ipv4Header &header,

Ptr<NetDevice> oif, Socket::SocketErrno &sockerr) {

Ptr<Ipv4Route> route = Create<Ipv4Route>();

StatelessRoutingHeader srHeader;

// Example: Define a static path for simplicity

std::vector<Ipv4Address> path = {Ipv4Address(“10.1.1.2”), Ipv4Address(“10.1.1.3”)};

srHeader.SetPath(path);

packet->AddHeader(srHeader);

route->SetDestination(header.GetDestination());

route->SetGateway(path[0]); // First hop

route->SetOutputDevice(oif);

return route;

}

• RouteInput: Forward packets according to the routing information in the header.

bool StatelessRouting::RouteInput(Ptr<const Packet> packet, const Ipv4Header &header,

Ptr<const NetDevice> idev, UnicastForwardCallback ucb,

MulticastForwardCallback mcb, LocalDeliverCallback lcb,

ErrorCallback ecb) {

StatelessRoutingHeader srHeader;

packet->PeekHeader(srHeader);

const auto &path = srHeader.GetPath();

if (header.GetDestination() == GetNode()->GetObject<Ipv4>()->GetAddress(1, 0).GetLocal()) {

lcb(packet, header, idev); // Deliver locally

return true;

}

if (!path.empty()) {

// Forward to the next hop

ForwardPacket(packet->Copy(), srHeader);

return true;

}

return false;

}

• ForwardPacket: Excerpt the next hop from the path and forward the packet.

void StatelessRouting::ForwardPacket(Ptr<Packet> packet, const StatelessRoutingHeader &header) {

const auto &path = header.GetPath();

if (!path.empty()) {

Ipv4Address nextHop = path[0];

std::vector<Ipv4Address> remainingPath(path.begin() + 1, path.end());

StatelessRoutingHeader newHeader;

newHeader.SetPath(remainingPath);

packet->AddHeader(newHeader);

Ptr<Ipv4Route> route = Create<Ipv4Route>();

route->SetDestination(nextHop);

route->SetGateway(nextHop);

route->SetOutputDevice(GetNode()->GetObject<Ipv4>()->GetNetDevice(0));

Simulator::ScheduleNow(&Ipv4RoutingProtocol::RouteOutput, this, packet, route, nullptr, Socket::ERROR_NOTERROR);

}

}

Step 5: Register the Protocol with NS-3

Store the protocol by NS-3’s TypeId system:

TypeId StatelessRouting::GetTypeId(void) {

static TypeId tid = TypeId(“ns3::StatelessRouting”)

.SetParent<Ipv4RoutingProtocol>()

.SetGroupName(“Internet”)

.AddConstructor<StatelessRouting>();

return tid;

}

Step 6: Integrate into a Simulation

1. Simulation Script Example:

#include “ns3/internet-stack-helper.h”

#include “ns3/stateless-routing.h”

int main(int argc, char *argv[]) {

NodeContainer nodes;

nodes.Create(4);

PointToPointHelper p2p;

p2p.SetDeviceAttribute(“DataRate”, StringValue(“10Mbps”));

p2p.SetChannelAttribute(“Delay”, StringValue(“2ms”));

NetDeviceContainer devices = p2p.Install(nodes.Get(0), nodes.Get(1));

devices.Add(p2p.Install(nodes.Get(1), nodes.Get(2)));

devices.Add(p2p.Install(nodes.Get(2), nodes.Get(3)));

InternetStackHelper stack;

Ptr<StatelessRouting> statelessRouting = CreateObject<StatelessRouting>();

stack.SetRoutingHelper(statelessRouting);

stack.Install(nodes);

Simulator::Run();

Simulator::Destroy();

return 0;

}

Step 7: Test and Debug

1. Enable Logging:

export NS_LOG=”StatelessRouting=level_all|prefix_time”

./ns3 run my-simulation

1. Validate:
   • Test the path-based sending.
   • Verify the packet delivery to the intended destination.

Step 8: Extend and Optimize

1. Enhancements:
   • Choose the dynamic path for enhance the terms on real-time network metrics.
   • Execute the fallback devices for path failures.
2. Performance Testing:
   • Validate the large-scale networks.
   • Investigate the scalability and packet overhead.

Through the entire process, you can acquire the simulation and execution process regarding the Stateless Routing project offered in it using ns3 tool. We will issue an additional document for questions related to this project.